Mind Map is a well-known graphical method to take notes. Instead of taking notes linearly so that they are read like an article, taking notes using mind map as shown in the figure has many advantages.
By arranging all information around a central theme, mind map provides a visual representation of the information, which is more intuitive to understand. They boost the recall of the information presented thus maximizing the retained learning. More importantly, since the ideas are presented in a radial, graphical, non-linear manner, mind maps help adopt a brainstorming approach to planning and organizational tasks.
To use mind map, all what you need is a paper and pen. But it becomes tedious when the mind map becomes bigger and bigger. Particularly, when you use mind maps for brainstorming, using paper and pen constraints your idea generation ability. During brainstorming we tend to get many new ideas, which require us to frequently reorganize the mind map. Doing it using paper and pen makes the mind map look messy. Also as we keep on adding new ideas and information, the mind map starts collecting more and more clutter, thus stifling further idea generation ability.
Using the software tool can help overcome these problems. By using software for creating mind map, we can add/delete ideas quite frequently without making the mind map messy. Also the software can provide a view where some branches can be collapsed or expanded thus giving non-cluttered view of the mind map.
There are quite a few mind-mapping software products available. Notable examples of commercial products include Buzan's iMindMap, MindManager (formerly known as MindMan) and XMind Pro. There are free software alternatives too. FreeMind is the one that I personally use for creating mind maps. It's easy to use and provides quite a good feature set. XMind is another free software product that can be considered.
Armed with a software product, you can effectively use mind maps thus increasing your productivity in learning and brainstorming!